1. Field of the Invention
This invention relates to a control valve, more particularly to a triple functional valve.
2. Description of the Related Art
Flow control valves, such as check valves, flow regulators and flowmeters are widely used in fluid systems. Check valves are used to restrict the direction of fluid flow. Flow regulators can regulate the flow rate of fluid. In the past, these flow control valves are individually designed, constructed and utilized in a fluid system.
FIGS. 1 and 2 show a conventional check valve and a conventional regulator, respectively. The conventional check valve has two separate housings, 91 and 92, which can be locked to each other in order to form a valve seat, and a plurality of preset devices for controlling the direction of fluid flow, the flow rate, etc., which are mounted individually in the valve seat. The conventional regulator has a construction similar to the conventional check valve and has a valve seat formed of two detachable housings, 93 and 94, and a plurality of preset controlling devices mounted in the valve seat. The structure and the assembly of the conventional check valve and regulator are complicated and troublesome, resulting in a high manufacturing cost.
FIG. 3 shows a variable area flowmeter which has a plug 81 that is movable in a tube member 82 in order to change the pass area of the aperture 83 through which the fluid flows. The tube member 82 has two holes, 84 and 85, which are to be connected to a transducer (not shown) in order to measure the differential pressure which has mathematic relationship with the flow rate in the tube member 82. Such a flowmeter is individually utilized in a fluid system, that is, there is no structural relationship between the flowmeter, the conventional check valve and the regulator in the fluid system. Since the flowmeter, the check valve and the regulator must be mounted separately on the fluid system, the arrangement and assembly of these control valves in the pipe-line of the fluid system are time-consuming and troublesome.